Condensed Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Revenue	$ 274,539	$ 264,405
Cost of goods sold	208,472	199,701
Gross profit	66,067	64,704
Operating expenses:
Selling, general and administrative expenses	61,167	53,615
Depreciation and amortization	3,659	2,904
Change in fair value of contingent consideration	0	(1,040)
Income from operations	1,241	9,225
Other income (expense):
Interest income	62	34
Interest expense	(1,568)	(1,003)
Other, net	(846)	(224)
Total other expense	(2,352)	(1,193)
(Loss) income before income taxes	(1,111)	8,032
Income tax expense	573	2,354
Net (loss) income	$ (1,684)	$ 5,678
Basic earnings (loss) per share (in dollars per share)	$ (0.03)	$ 0.11
Diluted earnings (loss) per share (in dollars per share)	$ (0.03)	$ 0.10
Comprehensive income	$ 1,680	$ 7,657